public class Student {

    public Student(){}

    public Student(String sname) {
        this.sname = sname;
    }

    public String sname {set; get;}

    public static String sex;
    
    public static Integer age {
        set {
            if(value < 1 || value > 100) {
                return;
            }
            Student.age = value;
        }
        get {
            return Student.age;
        }
    }

}